Strand treatment process



March 19, 1968 R.| .sTAN|.E-Y 3,374,302

STRAND TREATMENT PROCES S /Nslvrae vIMBERT K. STANLEY By f7 CM1- dakar'An-amn,

Mardi 19. 1968 R. K. STANLEY 3,374,302

STRAND TREATMENT PROCESS Filed Dec. 6, 1965 2 Sheets-Sheet 2 lam-wmf@ROBERT K. STANLEY Hc @KW7- www United States Patent 3,374,302 STRANDTREATMENT PROCESS Robert K. Stanley, Media, Pa., assignor toTechniservice Corporation, Lester, Pa., a corporation of PennsylvaniaContinuation-impart of application Ser. No. 476,933,

Aug. 3, 1965. This application Dec. 6, 1965, Ser.

4 Claims. (Cl. 264-168) ABSTRACT F THE DISCLOSURE A process of drawingand crimping textile strands is disclosed wherein the strand is pulledslidably over a snubbing surface, with cooling of the side of the strandin contact with the snubbing surface and simultaneous heating of theopposite side of the strand. The strand is withdrawn from the snubbinglocation and is subsequently relaxed, whereupon it obtains a bul-ky orcrimped configuration. Optional features of the process includepreheating the strand uniformly before reaching the snubbing locationand withdrawing the strand from the snubbing location under reducedtension and heating it substantially uniformly. A form of the product ischaracterized by concavity on the side of the strand previously cooledin contact with the snubbing surface and by convexity on the oppositeside previously heated.

This application is a continuation-in-part of my copending applicationSer. No. 476,933, tiled Aug. 3, 1965, for Strand Treatment.

This invention relates to drawing of molecularly orientable textilestrands to increased length and thereby orienting them, and concernsalso the crimping of such textile strands. Such a strand is pulledslidabl'y over a snubbing surface, and the side in contact with thesnubbing surface is cooled, while the opposite side is heated, whereuponthe -strand acquires an extended length and a bulky or crimpedconguration.

Many textile strands, especially those composed of synthetic organicpolymers of linear structure, are molecularly orientable by a procedureof extending the strand beyond its elastic limit or drawing it,whereupon the strand does not break but attains a stable extendedlengthby virtue of longitudinal alignment and possibly slippage of thecomponent polymeric molecules. Such procedure usually involves pullingthe strand about a solid snubbing surface, most often cylindrical, andfrequently involves heating the strand or the snubbing surface or both.

A primary object of the present invention is improvement instrand-drawing.

Another object is provision of crimped strands by way of a novel drawingtechnique.

A further object is provision of a draw-crimping process and apparatusfor practicing it.

Other objects of this invention, together with means and methods forattaining the various objects, will be apparent from the followingdescription and the accompanying diagrams.

FIG. 1 is a representation, partly in elevation and partly in schematicform, of apparatus according to the present invention;

FIG. 2 is la similar view on a reduced-scale, of further apparatusaccording to this invention and of crimped strand produced thereby;

FIG. 3 is a representation, partly in elevation and partly in schematicform, of a portion of the apparatus of FIG. 1 with one of the componentheaters displaced from its former position;

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FIG. 4 is a similar view with the same heater otherwise displaced fromits former position;

FIG. 5 is a further view of the same heater partly in side elevation andpartly in schematic form;

FIG. 6 is a similar view of the same heater modified somewhat;

FIG. 7 is a view, partly in side elevation and partly in schematic form,of a uid supply system with the heater of FIG. 6; and

FIG. 8 is a lview, partly in elevation and partly in schematic form, ofanother modification of such heater.

In general, the objects of the present invention are accomplished bypulling a molecularly orientable textile strand over a snubbing surfaceto draw it to increased length and thereby orient it, and simultaneouslycooling the strand while in contact therewith and heating the oppositeside of the strand. Upon subsequent relaxation from tension, with orwithout the aid of heat, the strand assumes a crimped configuration.

FIG. l shows strand 11, of molecularly orientable type, being fed bypair of feed rolls 12, 13 toward the upper right, past heater 14 and tosnubbing member 15, which has semicylindrical snubbing surface 16. Thestrand is pulled over the snubbing surface by pair of draw rolls 17, 18and past heater 2.4 juxtaposed to the opposite side of the strand `andis thereby extended (after which it is denoted as 11'). Block 19 denotesdrive means for the rolls by means of suitable drive linkages (indicatedin broken lines): 19a to feed roll 13, 19b to draw roll 17, and 19e to aroll discussed hereinafter. The drive means comprises either an engineor an electric motor (not shown) together with suitable gearing l(alsonot shown) so that the respective pairs of lrolls can be driven at anydesired angular speeds and any desired speed ratio. The second roll ineach pair may be undriven except by contact with the driven roll and thestrand passing through the roll nip, or both rolls in any pair may bed-riven alike (but in opposite directions). The draw rolls are driven ata greater surface speed than the feed rolls, preferably several times asgreat, the actual speed Iratio depending upon the drawability of thestrand composition and the desired degree of draw to be accomplished.

Snubbing member 15 is provided with conduits 21 and 23, shown witharrows leading respectively to and from the snubbing member, which ishollow (as indicated n broken lines) to interconnect them, andrespectively from and to block 25, which represents circulation-inducingmeans and heat sink. Thus, where the circulating material is arefrigerant liuid, for example, the conduits and the interconnectionthereof in the snubbing member comprise the cooling coil, the rest of aconventional refrigerator being represented by block 25, and enlargedportion 22 of the interconnection in the interior of the snubbing memberrepresenting a plenum chamber, preferably supplied with fins to the bodyof the member for ready heat-exchange therewith. Alternatively, conduits21 and 23 may be simply electrical conductors (the arrows representingelectrical current flow therein), in which event block 25 represents aD.C. generator, battery, or equivalent source, and enlarged portion 22in the snubbing member represeents a thermoelectric device (e.g., aPeltier junction or group thereof) adapted to produce a cooling effectupon current liow therethrough in the indicated direction, the selectionof which is Well within the capability of a person skilled in the art.

Heater 24 extends for substantially the entire width (i.e.,perpendicular to the plane of FIG. 1 and the succeeding views) ofsnubbing surface 16 or so much there of as is covered by the strandbeing drawn thereover. The tip ofthe heater is tapered to concentratethe heating elect at a narrow line across the snubbing surface, ascompared with the arcuate extent of the snubbing surface over which thestrand travels, so as to provide substantially point heating of thestrand. A differential or gradient in temperature is produced in thestrand, extending transversely thereof, to the cool side of the strandin contact with snubbing surface 16, from the opposite side heated(momentarily) by heater 24.

This heater preferably does not actually come into contact with thestrand unless modified for rolling contact therewith as describedhereinafter. Various theoretical reasons (more apparent after the factthan before) may be advanced for the beneficial results of providingsuch a temperature gradient across the strand at or in the vicinity ofthe locus where the drawing to increased length occurs. Likewise, theeffect upon the internal molecular arrangement is somewhat speculative,so this invention is not limited by any particular theoreticalconsiderations or confined to any specific internal rearrangement, butrather is defined only by the claims appended hereto.

FIG. 2 shows (on a reduced scale) drawn strand 11' proceeding to theright past heater 27 to pair of strandforwarding rolls 28, 29 driventhrough linkage 19e (indicated in broken lines) at reduced tension and ausually intermediate surface speed sufficient, however, to maintain inthe strand at least some of the tension imparted by the strand-drawingrolls despite any change in length induced by heater 27 when on. Thisremaining tension, which may be only suliicient to prevent slack in thestrand, is released as the roll nip releases the strand (then denoted as11) into relaxed crimped configuration, which is shown somewhatstylized. If desired, the strand-forwarding rolls may be omitted and thetension be released at the nip of the strand-drawing rolls. Also, ifdesired the strand-feeding rolls may be replaced by equivalentstrandrestraining means effective to ensure adequate contact between thestrand and the surface of the snubbing member as the stand-drawing rollspull the strand thereover. The relaxation step, which induces stressrelief in the strand, may be repeated, if desired, with or withoutvariation therein.

Use of either or both of heaters 14 and 27 may -be dispensed with as maybe desired. Heater 14, which is a preheater to facilitate drawing as isdesirable with some strand compositions, may be replaced upon providingone or both of feed rolls 12, 13 with internal heating means, such asthat shown and described for the feed rolls of a stuffer crimper in myPatent 3,111,740. Alternatively, with strands of readily drawablecompositions, heater 14 may be removed without such modification of thefeed rolls (or simply be left in place but not turned on), as thefriction of the strand against snubbing surface 16 and theintermolecular friction engendered as the strand begins to draw willinduce a heating of the strand. Of course, the cooled snubbing memberacts to remove heat of whatever origin, including that provided byjuxtaposed heater 24, from the drawing or drawn strand; however, unlikethose other two heaters, it does not act uniformly on the strand butcontacts it along one side only. Heater 27 is used to heat-relax thedrawn strand wherever the latent crimp is not developed to the extentdesired upon simply relaxing the strand -by releasing it from tension.Where not required it can be removed or left in place turned off. Aheat-relaxation aftertreatment may be employed instead of or in additionto heat-relaxation by heater 27. Both heaters 14 and 27 may be of anysuitable design, such as an enclosure supplied with radiant energy,steam, or other means of heat-transfer, or simply a heated block overwhich the strand travels in heat-conductive contact.

Heater 24 may be similarly provided with heat energy for transmission tothe strand by radiation, convection, conduction or combination thereof.It need not be located at the midpoint of snubbing surface 16 of thesnubbing member (as viewed from the side) but may be displacedthroughout the arcuate range within which the Strand is in contact withthe snubbing surface. Thus, FIG. 3 shows heater 24 relocated at aboutthe point of initial tangency, and FIG. 4 shows it at about the point offinal tangency, of the strand with the snubbingsurface (but at theopposite side of the strand therefrom, of course). While more than onesuch heater may be employed, at the illustrated locations or at pointstherebetween, that usually is not necessary. Regardless of whether oneor more than one such juxtaposed heater is used, the location shown inFIG. 3 can be especially useful where no preheater 14 is used, and thelocation shown in FIG. 4 is helpful for strands that draw principally ator near that point.

Snubbing member 15, and particularly snubbing surface 16 thereof, iscomposed of any suitably hard material having suitably highheat-conductivity characteristics, usually a metal or alloy thereof.Conventional steel draw pins often are suitable for such member and maybe cut in half longitudinally and hollowed if necessary. Asemicylindrical snubbing surface is most convenient, as the strand doesnot wrap one or more turns about the member as is customary inconventional drawing operations with cylindrical draw pins but passesthereover through a preferred angle of about a radian of arc, or atleast about a half radian and at most about two radians. Of course, anon-arcuate curved surface may be used, if desired. In either event theaverage radius of curvature of the snubbing member should be large withrespect to the filamentary diameter of the strand, and for the purposesof this invention large means a minimum ratio of about one hundredtimes. For most purposes the snubbing member will be selected to have aradius of not less than about one centimeter nor more than about tencentimeters.

Suitable temperatures or ranges thereof for the snubhing member, thejuxtaposed heater, and the preheater (if used) depend upon the strandcomposition, period of exposure thereto, and heat-transfercharacteristics. An undrawn 6-nylon strand of forty four hundred totaldenier and sixty-eight filaments fed at two and one-half meters perminute (4X draw) without preheatin-g, through slightly more than 30 ofarc over the surface of a cylindrical snubbing member having a diameterof about ten centimeters and maintained at Va temperature of 20 to 25C., to which was juxtaposed a heater as in FIG. 1 having a temperatureof about 200 C. at the tip, assumes upon release of tension therein acoiled or curly crimped configuration. The crimp is intensified byaftertreatment of the entire strand at a temperature in the range ofabout C. to a temperature approaching that of the juxtaposed heater. Asimilar strand subjected to treatment in identical manner except foromission (or inactivation) of the juxtaposed heater exhibits aconsiderably lesser degree of crimp, which although useful is either notas bulky or (even if as bulky) not as resilient and, therefore, not sowell suited for hard usage applications.

The strand may be -a monofilament or multifilament and may range in sizefrom as small as one or two to fifteen or more denier per filament. Inthe instance of multitilament strands the total denier may be in thehundreds or even the thousands. In the instance of multifilament eachcomponent filament of the strand should have a diameter of at most aboutone one-hundredth of the radius of curvature of the snubbing surface. Inthe processing of large bundles of filaments it is preferred to spreadthem laterally by any suitable means to ensure that the individualfilaments are gripped securely by the rolls and are brought intorelatively good heat-exchanging relation to the heaters (when used) andthe snubbing member. The removal of heat from each filament of thestrand by means of the snubbing member during drawing induces atransverse non-uniformity therein, which although only imperfectlyunderstood induces a most satisfactory crimp, the full extent of whichmay become apparent only upon subsequent relaxation of the strand,performed one or more times.

.Articles made by knitting, weaving, or otherwise fabricating suchstrands, with lor without addition of other strands or materials,exhibit desirable characteristics of cling, cover, elasticity, and thelike. The invention provides such strands by a rapid, readilycontrolled, and inexpensive technique. It may be incorporated in themanufacturing line of a plant in which synthetic strands of molecularlyorientable compositions are extruded from melts or solutions thereof.

FIG. 5 shows, partly in side elevation and partly in schematic form, anembodiment of heater, designated as 24', for juxtaposition to the strandand designed principally for radiant heating of the side thereofopposite the side in contact with the snubbing surface. This heater isfurnished with a pair of electrical leads 31 and with interconnectedinternal resistance heating element (indicated in broken lines). Ifdesired, the heater (suit-ably hollowed) may be supplied with heated uidthrough pipelines substituted for the electrical leads. In either eventheat radiating from the tip of the heater raises the temperature of theside of the strand to which it is juxtaposed as in the preceding views.

FIG. 6 shows similarly, but on an enlarged scale, another embodiment ofsuch heater, designated as 24", designed principally for convectiveheating of the side of strand to which it is juxtaposed. This heater ishollow inside (as indicated by broken lines) and open at the tip for owof fluid therefrom (as indicated by arrows). FIG. 7 shows, largelyschematically, heater 24" interconnected into -a uid supply system. Thesystem comprises source 35 of uid, heater 36 therefor, andinterconnecting piping 37 (to heater 24) containing pump P between thefluid source and heater 36. Flow of the fluid out the tip of heater 24"raises the temperature of the adjacent side of the strand. The fluid maybe gas or vapor, such as hot air or steam, or may be liquid, preferablynon-wetting for the strand (eg, a molten metal). If desired, heater 24may be modiiied to accommodate combustible gas and to jet the resultingflame or hot combustion product onto the strand, although care must betaken not to degrade the strand by excessive heating or chemical action.

FIG. 8 shows, also partly in side elevation and partly in schematicform, a further embodiment of such heater, designated as 24', designedprincipally for conductive heating of the strand upon juxtaposition tothe side of the strand opposite the snubbing surface. Here the tip ofthe heater housing is spaced from the strand much as in the previousembodiments, but the intervening space is occupied by a sector of theroller protruding from the tip. As the strand slides over the coolsnubbing surface, the roller rotates in essentially non-slipping contactwith the opposite side of the strand and raises the temperature thereofby exchange of heat therewith. The roller normally is free-running,being rotated only by Contact with the strand, although it may be drivenby appropriate means if desired, either more slowly or preferably morerapidly than the rate of travel of the strand over the snubbing surface.The maj-0r part of the roller being inside the heater tip is heatedthere by any of the means utilized in the previously described andillustrated heaters for juxtaposition to the strand, providing good heattransfer thereto via the minor exposed part of the roller as it rotatesout from the tip and into Contact with the strand. Also, if desired,when uid heating is employed, some of the fluid may be permitted toescape therefrom over or past the roller and onto the strand.

Although particular apparatus embodiments have been illustrated anddescribed and certain modifications suggested, other modifications maybe made therein while retaining at least some of the benefits of thepresent invention, which itself is defined only in the following claims.

The claimed invention is:

1. irocess of drawing and crimping a textile strand including at leastone continuous filament drawable to increased length, comprising pullingthe strand slidably over a snubbing surface at a snubbing location andthereby Iocalizing the drawing of the strand to increased length at thesnubbing location, cooling the side of the strand in contact with thesnubbing surface, simultaneously heating the opposite side of the strandat the snubbing location, withdrawing the strand from the snubbinglocation, and subsequently relaxing the strand.

2. The process of claim 1 wherein the strand is preheated substantiallyuniformly before reaching the snubbing location.

3. The process of claim l wherein the strand is forwarded under reducedtension after being withdrawn from the snubbing location and is heatedvsubstantially uniformly while under reduced tension.

4. The process of claim 1 wherein the snubbing surface is convex, theside of the strand cooled in contact therewith is by such contactrendered concave, the heated opposite side of the strand is by suchcontact rendered convex, and the respective sides remain concave andcon- Vex after subsequent relaxation of the strand.

References Cited UNITED STATES PATENTS 2,613,697 10/1952 Fantell 28-723,113,366 1.2/1963 Taylor 28-1 3,174,208 3/1965 Saito et al. 28-723,224,068 12/ 1965 Edington et al. 28-72 FOREIGN PATENTS 225,883 12/1919Australia. 907,823 10/ 1962 Great Britain.

LOUIS K. RIMRODT, Primary Examiner.

